Spotted Wing Drosophila Alert:  10/14/2022

Male and Female Spotted Wing Drosophila
Male and Female Spotted Wing Drosophila; image by Alan Kenage, Capital Press. Used with permission.

David Handley, Vegetable and Small Fruit Specialist; James Dill, Pest Management Specialist, Phil Fanning, Assistant Professor of Agricultural Entomology, Christina Howard, New Farmers Program Manager


This will be the last planned issue of the Spotted Wing Drosophila Alert for the 2022 season.  We like to thank all of the farms that volunteered to be SWD trapping sites, and our scouts, Karla Mendoza Yanes and Brooke Martin for collecting trap catches every week.


Drosophila Trap
Drosophila Trap, photo by David Handley

Spotted wing drosophila fly counts remain very low for this time in the season at all sites this week.   While the reason for this is unclear, it may result in a low overwintering population and thus a smaller population to begin next year’s season. Populations have not been this low at this point in the season since we started statewide trapping in 2012.  While most berry farms have finished for the season, fly counts are still high enough to require protection of any berries remaining in the field that you want to harvest.


A 5-7-day spray schedule is recommended on all soft-fruited crops, including fall raspberries, blackberries, and day neutral strawberries, where populations exceed the threshold of more than six flies caught in a week.


For more information on identifying spotted wing drosophila (SWD) and updates on populations around the state, visit our SWD blog at:  Spotted Wing Drosophila Archives – Cooperative Extension at Highmoor Farm (


Other IPM Web Pages
Michigan State University:  Michigan State University Extension – Spotted Wing Drosophila Information

Penn State University:  Penn State University Extension’s Spotted Wing Drosophila Overview


David T. Handley
Vegetable and Small Fruit Specialist

Highmoor Farm, P.O. Box 179, Monmouth, ME 04259   207.933.2100

Pest Management Unit, 17 Godfrey Dr., Orono, ME 04473   1.800.287.0279

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Town SWD weekly trap catch 9/23/22 SWD weekly trap catch 9/30/22 SWD weekly trap catch 10/6/22 SWD weekly trap catch 10/14/22
Wells 214 44 14 63
Limerick 13 7 3 11
New Gloucester 227 29 53 53
Bowdoinham 292 74 57 81
Mechanic Falls 1,208 108 62 6
Monmouth* 1,320 790 614 465
Wayne 721 77 39 34

Weekly spotted wing drosophila trap captures.

*Unsprayed plot